feat: locale packs so non-English calls are not silent passes

[AshSgDe29071999]

Summary

Mishearing and confirmation vocabularies were hardcoded English. A Spanish or Hindi call returned empty findings from the two most important checks — the same silent-pass shape this project exists to catch.

Changes

• `voiceeval/locale_packs/{en,es}.json` with confusable pairs + confirmation phrases
• `Interaction.language` (default `en`); `analyse(..., packs=..., locale_pack=...)`
• Missing pack → `locale_unavailable` (high) so the suite does not pass
• English default pack matches the previous in-code lists
• Spanish example pack + `fixtures/misheard_es.json`
• Suites can pass their own pack

Test plan

• `python3 -m pytest -q tests/test_voiceeval.py` (22 passed)
• `good_call.json` still has zero findings under `en`

Fixes #3

[royalpinto007]

Locale packs are the right call, and locale_unavailable at high severity instead of an empty result is better than I would have asked for. Verified: language=hi gives [(locale_unavailable, high)], en clean call gives nothing.

Same matching bug as #9, written independently here:

FLAGGED  "I ordered fifteen items for fifty pounds"       <- transcript == truth
FLAGGED  "we have thirteen in stock and thirty on order"  <- transcript == truth

Only the -teen/-ty pairs are in en today so it is rare, but once #9 adds to/two and a/eight it fires constantly.

Suggest landing this one first with a positional matcher (difflib opcodes, pairs taken from the pack), then rebasing #9 so it only adds pairs and a fixture. One matcher, one place.

[royalpinto007]

Missing locale packs currently stop all analysis, hiding language-independent findings like policy violations, latency, and incomplete calls. Please add locale_unavailable, skip only locale-dependent checks, and continue running the others.